Air filter assemblies and carrier frames having vortex-generating flow guide

ABSTRACT

Air filter assemblies and carrier frames have a plurality of vortex-generating flow guides normalizing air flow to a uniform velocity profile downstream thereof. The airflow having the uniform velocity profile travels across a mass airflow sensor.

CROSS-REFERENCE TO RELATED APPLICATION

The present U.S. Utility Patent Application claims the benefit of andpriority to U.S. Provisional Patent Application Ser. No. 61/725,511,filed Nov. 13, 2012, which hereby is incorporated herein by reference.

FIELD AND BACKGROUND

The present disclosure relates to air filter assemblies and carrierframes for air filter assemblies, particularly air filter assemblieshaving an airflow sensor. The present disclosure arose during continuingdevelopment efforts directed toward air filtration.

U.S. Pat. No. 6,391,076, the disclosure of which is hereby incorporatedherein by reference in entirety, discloses a full flow fluid filterhaving a housing extending axially along an axis, and a pleated filterelement having a plurality of pleats in a closed loop annulus having anouter perimeter defined by a plurality of outer pleat tips, an innerperimeter defined by a plurality of inner pleat tips, and a hollowinterior extending along the axis. Fluid flows substantially directlyaxially through the filter element, with minimal bending and change ofdirection, minimizing flow restriction.

U.S. Patent Publication No. 2006/0065592, the disclosure of which ishereby incorporated herein by reference in entirety, discloses a directflow filter having seal tips alternately sealing upstream and/ordownstream ends of wall segments to each other to define first andsecond sets of flow channels and protecting the ends of the wallsegments from damage, including upstream ends from incoming debris, andproviding structural support withstanding high flow rates and improvingflow by means of the geometry of the seal.

U.S. Pat. No. 7,314,558, the disclosure of which is hereby incorporatedherein by reference in entirety, discloses a pleated panel fluid filterfiltering fluid flowing along an axial flow direction and includesangled panels and/or progressively increasing flow channel width and/orskewed panel projections and/or flattened pleat tip bend lines.

U.S. Pat. No. 7,323,106, the disclosure of which is hereby incorporatedherein by reference in entirety, discloses a filter with multiplepleated filter elements having axially extending channels having atransverse pleat channel height and a lateral channel width. The pleatedfilter elements have different channel heights.

U.S. Pat. No. 7,540,895, the disclosure of which is hereby incorporatedherein by reference in entirety, discloses a filter including a housingwith multiple flow passages and filter elements, including at leastfirst and second flow passages therethrough including respective firstand second filter elements in parallel. Respective internal, dividingwalls separate flow passages in space saving relation.

U.S. Patent Publication No. 2008/0011673, the disclosure of which ishereby incorporated herein by reference in entirety, discloses a directflow filter having one or more upstream and/or downstream face sealstransversely spanning from one set of pleat tips at least partiallytowards the other set of pleat tips and laterally spanning adjacentchannels.

U.S. Pat. No. 7,879,125, the disclosure of which is hereby incorporatedherein by reference in entirety, discloses a filter provided by pleatedfilter media having a plurality of pleats defined by wall segmentsextending axially along an axial direction along an axis and extendingtransversely along a transverse direction between first and second setsof pleat tips at first and second sets of axially extending bend lines.The pleated filter media spans laterally along a lateral span along alateral direction, with the wall segments being spaced from each otherby lateral gaps. The pleats have a pleat depth along the transversedirection along the wall segments between the first and second sets ofpleat tips. The pleat depth varies as the pleated filter media spanslaterally along the lateral direction.

U.S. Patent Publication No. 2013/0062276, the disclosure of which ishereby incorporated herein by reference in entirety, discloses a pleatedfilter element comprising a plurality of pleats comprised of pleatsegments extending in an axial direction between first and second axialends and extending in a transverse direction that is perpendicular tothe axial direction between first and second sets of pleat tips at leastpartially defined by first and second sets of bend lines. Axial flowchannels are defined between the pleat segments in the lateral directionand the plurality of pleats has a width in the transverse direction thatvaries along the axial direction.

SUMMARY

In certain examples disclosed herein, carrier frames are for supportingair filter elements having a dirty air inlet and a clean air outlet andfiltering air flowing therethrough from upstream to downstream. Thecarrier frames can have an exit side at the clean air outlet, the exitside having at least one vortex-generating flow guide promoting rapidmixing of clean air downstream of the air filter element andnormalization of a uniform velocity profile downstream thereof for flowto a mass airflow (MAF) sensor, to thereby minimize MAF variation due toimperfect air filter element construction.

In certain examples disclosed herein, air filter assemblies have afilter element that filters air flowing from an upstream inlet to adownstream outlet. A carrier frame carries the filter media. A pluralityof vortex-generating flow guides are located at the outlet. Theplurality of vortex-generating flow guides normalize airflow to auniform velocity profile downstream thereof. A MAF sensor is providedacross which the airflow having the uniform velocity profile travels.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an example of an air filter assemblyaccording to the present disclosure.

FIG. 2 is a closer view of FIG. 1 showing a plurality ofvortex-generating flow guides at an outlet end of the air filterassembly.

FIG. 3 is a sectional view along section 3-3 in FIG. 1.

FIG. 4 is a perspective view of one example of a carrier frame havingthe plurality of vortex-generating flow guides.

FIG. 5 is a closer view of FIG. 3 showing one of the vortex-generatingflow guides.

FIG. 6 is a top view of the carrier frame shown in FIG. 3.

FIG. 7 is a front view of the carrier frame shown in FIG. 3.

FIG. 8 is a side view of the carrier frame shown in FIG. 3.

FIG. 9 is a perspective view of a vortex-generating flow guide shown inFIG. 4.

FIG. 10 is another perspective view of the vortex-generating flow guidesshown in FIG. 4.

FIG. 11 is perspective view of another example of a carrier frame havingthe plurality of vortex-generating flow guides.

FIG. 12 is a top view of the carrier frame shown in FIG. 11.

FIG. 13 is a side view of the carrier frame shown in FIG. 11.

FIG. 14 is a perspective view of a vortex-generating flow guide shown inFIG. 11.

DETAILED DESCRIPTION

In the present description, certain terms have been used for brevity,clearness and understanding. No unnecessary limitations are to beimplied therefrom beyond the requirement of the prior art because suchterms are used for descriptive purposes only and are intended to bebroadly construed. The different air filter assemblies and carrierframes described herein may be used alone or in combination with otherapparatuses. Various equivalents, alternatives and modifications arepossible within the scope of the appended claims. Each limitation in theappended claims is intended to invoke interpretation under 35 U.S.C.Section 112, sixth paragraph only if the terms “means for” or “step for”are explicitly recited in the respective limitation.

FIGS. 1-3 depict an air filter assembly 20 for filtering air flowingalong an axial direction 22 from an upstream inlet end 24 to adownstream outlet end 26. In this example, the air filter assembly 20 isa direct airflow filter arrangement having an upstream primary filterelement 30 and a downstream secondary filter element 32; however thisexample is not intended to be limiting and the concepts of the presentdisclosure are also applicable to other types of conventional filterassemblies, including indirect filter assemblies and filter assemblieshaving one, or three or more filter elements. In the example shown, fromupstream to downstream, the air filter assembly 20 has a conventionalpre-cleaner 28, the noted primary filter element 30 that filters theairflow from upstream to downstream, and the noted secondary filterelement 32 that filters airflow from upstream to downstream. The primarytitter element 30 has a dirty air inlet end 34 and a clean air outletend 36 located downstream of the dirty air inlet end 34. The secondaryfilter element 32 has a dirty air inlet end 38 and a clean air outletend 40 located downstream of the dirty air inlet end 38. Furtherdiscussion of this type of filter assembly can be found in theincorporated patent documents referenced herein above.

The secondary filter element 32 is carried by a carrier frame 42supported in a housing 44 of the air filter assembly 20. The carrierframe 42 has an exit side 46 positioned downstream and adjacent theclean air outlet end 40 on the secondary filter element 32. Thesecondary filter element 32 is supported in the housing 44 by thecarrier frame 42. The carder frame 42 provides a first seal 43 betweenthe carrier frame 42 and the secondary filter element 32 and a secondseal 45 between the carrier frame 42 and the housing 44, therebypreventing bypass of unfiltered dirty air to the downstream outlet end26 in the event of rupture or damage to the secondary filter element 32.

The air filter assembly 20 also has a conventional mass airflow (MAF)sensor 51 across which the air flows. In this example, the MAF sensor 51is located in a sidewall 53 of the housing 44 at the downstream outletend 26 and senses air flow downstream of the primary and secondaryfilter elements 30, 32. In other examples, the air filter assembly 20can include more than one MAF sensor 51 and the location of the MAFsensor(s) 51 can vary from that shown. The MAF sensor can communicatewith an engine control unit (not shown) for providing feedback andengine control, as is conventional.

Through experimentation, the present inventors have found thatimperfections in manufacture of filter elements, such as pleated filterelements, cause part-to-part velocity variations in the airflow thatpersist in the downstream outlet end and create flow variability, whichresults in variability of the output of the MAP sensor 51. Among otherthings, these imperfections can be the result of pleat bunching,pinching, and/or embossments in the primary and secondary filterelements 30, 32, such as the secondary (safety) filter element 32. Thepresent disclosure relates from endeavors to minimize such variations inthe output of MAF sensor 51.

FIGS. 4-10 depict one example of the carrier frame 42 according to thepresent disclosure. The carrier frame 42 includes a plurality ofvortex-generating flow guides 50 that promote rapid mixing of clean airdownstream of the secondary filter element 32 and normalization of auniform velocity profile downstream thereof for flow to the MAF sensor51, to thereby minimize output variation of the MAF sensor 51 due toimperfect air filter element construction. As will be apparent from thefollowing discussion, the number, location, orientation, size andphysical configurations of the vortex-generating flow guides 50 can varyfrom that shown. The carrier frame 42 can have as few as onevortex-generating flow guide 50. The vortex-generating flow guides 50can be molded with the exit side 46 of the carrier frame 42. In otherexamples, the vortex-generating flow guides 50 can be separatecomponents that are attached to the carrier frame 42 for example by asnap fit, by one or more clips, or by other conventional attachmentmeans.

In use, air flows from the upstream inlet end 24 through the pre-cleaner28, through the primary filter element 30 and through the secondaryfilter element 32. The air flows out of the clean air outlet end 40 onthe secondary filter element 32 along a generally axial flow path 22until it flows along the vortex-generating flow guide 50 on the carrierframe 42. Because of imperfections in the filter elements, such as theprimary and secondary filter elements 30, 32, the air exiting thesecondary filter element 32 typically has a non-uniform velocityprofile. Advantageously, the vortex-generating flow guides 50 redirectthe airflow into at least one vortex flow path 52, thus normalizing of auniform velocity profile downstream thereof for flow to the MAF sensor51, to thereby minimize mass airflow variation due to imperfect airfilter element construction.

In the example shown in FIGS. 4-10, the vortex-generating flow guides 50include pairs of tilted trapezoidal tabs 54, which are tilted at someangle from the axial flow path 22 and mounted in a radially staggeredpattern or array on the carrier frame 42 to thereby maximize the numberof vortex flow paths 52 (see FIGS. 3 and 5) that spin radially away fromthe axial flow path 22 in the upstream-to-downstream direction. Thevortex flow paths 52 induce rapid mixing and dissipation ofnon-uniformity in the velocity profile exiting the secondary filterelement 32, as can be generated by an imperfect filter elementconstruction. In this particular example, the pairs of tiltedtrapezoidal tabs 54 have like geometry and are tilted at opposite butequal tilt angles (T) (see FIG. 10) with respect to the axial flow path22. Each tilted trapezoidal tab 54 is planar and has parallel, opposingelongated upstream and downstream edges 58, 60 that both extendperpendicular to the axial flow path 22. The upstream edge 58 is longerthan the downstream edge 60. Each tilted trapezoidal tab 54 also hasopposing elongated side edges 62 a, 62 b that extend from the upstreamedge 58 to the downstream edge 60 at an edge angle (E). The trapezoidaltabs 54 in each pair have adjacent upstream edges 58 and spaced apartdownstream edges 60 and thereby define a V-shape when viewed incross-section, see FIG. 7.

As shown in FIG. 6, the exit side 46 of the carrier frame 42 has aplurality of pairs of trapezoidal tabs 54 that form the noted radiallystaggered array, which includes interdigitated first and second rows 66,68 of pairs of trapezoidal tabs 54, the first row 66 having less pairsof trapezoidal tabs 54 than the second row 68. The pairs of trapezoidaltabs 54 in the first row 66 have elongated upstream edges 58 that areparallel with respect to the upstream edges 58 of the second row 68 ofpairs of trapezoidal tabs 54. The pairs of trapezoidal tabs 54 in thefirst rows 66 are radially offset or staggered from the pairs oftrapezoidal tabs 54 in the second row 68. The pairs of trapezoidal tabs54 in both the first and second rows 66, 68 are spaced apart from theother pairs of trapezoidal tabs 54 in the respective row by a spacing(S). A plurality of spaced apart cross ribs 70 support the staggeredarray of pairs of trapezoidal tabs 54.

FIGS. 4-10 illustrate the upstream edges 58 of all trapezoidal tabs 54being parallel on the carrier frame 42; however in one of the manypossible alternative arrangements that are contemplated by thisdisclosure, the upstream edges 58 of some of the pairs of tiltedtrapezoidal tabs 54 in the plurality can be staggered at 90 degreeangles relative to the upstream edges 58 of other pairs of tiltedtrapezoidal tabs 54 in the plurality. For example the pairs oftrapezoidal tabs 54 in the first row 66 can be radially oriented 90degrees from the pairs of trapezoidal tabs 54 in the second row 68 suchthat the upstream edges 58 of the pairs of trapezoidal tabs 54 in thefirst row 66 are radially oriented 90 degrees from the upstream edges 58of the pairs of trapezoidal tabs 54 in the second row 68. Alternately,the upstream edges 58 of the pairs of trapezoidal tabs 54 in the firstand second rows 66, 68 can be arranged at other angles with respect toeach other. Alternately, the upstream edges 58 of the pairs oftrapezoidal tabs 54 in each of the first and second rows 66, 68 can bearranged at different angles than other trapezoidal tabs 54 in the samefirst and second row 66, 68. The pairs of trapezoidal tabs 54 could alsobe arranged in an axially staggered pattern, wherein certain trapezoidaltabs 54 are located further upstream and/or downstream of othertrapezoidal tabs 54 in the plurality.

The geometrical dimensions of the trapezoidal tabs 54 can also vary fromthat shown in the figures. Dimensional parameters of the trapezoidaltabs 54 include the lengths of the upstream and downstream edges 58, 60,the height (H) of the side edges 62 a, 62 b, the ratio of the length (L)of the upstream edge 58, to the height (H) of the side edges 62 a, 62 b,and angle of tilt (T) of the tilted trapezoidal tabs 54 to the axialflow path 22, the angle (E) of the side edges 62 a, 62 b, and thespacing (S) between the pairs of tilted trapezoidal tabs 54. In thedrawings, the edge angle (E) equals 30 degrees, the tilt angle (T)equals 28 degrees, the height (H) of the side edges 62 a, 62 b equals 8millimeters, the length (L) of the upstream edges 58 equals 14millimeters, the length (L) to height (H) ratio equals 0.57, the tabspacing (S) equals 6 millimeters, and the tab spacing (S) divided bylength (L) equals 0.42. However these dimensions can vary based uponvarious factors including the particular configuration of the air filterassembly 20. In certain examples, the edge angle (E) can vary from 0-45degrees, the tilt angle (T) can vary from 10-45 degrees, the tab height(H) can vary from 5 millimeters to 35 millimeters, tab length (L) canvary from 5 mm to 35 mm, the length (L) to height (H) ratio can varyfrom 0.25 to 4, and the tab spacing (S) to length (L) ratio can varyfrom 0.1 to 2. Other combinations are possible and contemplated.

FIGS. 11-14 depict another example of a carrier frame 42 having aplurality of vortex-generating flow guides 50. In this example, thevortex-generating flow guides 50 include helical vanes 80. Each helicalvane 80 has an elongated upstream edge 82 and an elongated downstreamedge 84. The elongated upstream edge 82 is orientated at a twist angle(A) with respect to the elongated downstream edge 84. Opposing helicalside edges 88, 90 extend between the upstream and downstream edges 82,84. A helical surface 92 directs airflow in the noted vortex flow path.

As shown in FIG. 12, the helical vanes 80 are arranged on the exit side46 of the carrier frame 42 in a radially staggered pattern or array thatincludes interdigitated first and second rows 94, 96 of helical vanes80. The first rows 94 have more helical vanes 80 than the second rows 96and the helical vanes 80 in the first row 94 are radially offset fromthe helical vanes 80 in the second row 96. A plurality of radiallyspaced apart cross ribs 98 form a grid that supports the radiallystaggered array of helical vanes 80. The elongated upstream edge 82 andelongated downstream edges 84 of the helical vanes 80 in the first row94 are offset 180 degrees when compared to the elongated upstream edgesand elongated downstream edges 82, 84 of the helical vanes 80 in thesecond row 96. As such, the helical vanes 80 in the first rows 94 haveupstream edges 82 that are transversely orientated from the upstreamedges 82 of the helical vanes 80 in the second row 96.

The geometrical parameters for the helical, vanes 80 can vary andinclude vane width (X), vane height (Y), vane depth (Z), ratio of vanewidth (X) to vane height (Y), and degrees of twist (A) and/or pitch (P)angle. The drawings depict helical vanes 80 having, a vane width (X) of19 millimeters, a vane height (Y) of 15 millimeters, a height (Y) towidth (X) ratio of 0.79, and a twist angle (A) of 90 degrees. In certainexamples, the vane width (X) can range from 5 to 25 millimeters, thevane height (Y) can range from 5 to 25 millimeters, the twist angle (A)can range from 10 to 220 degrees, the pitch angle (P) can range from 10to 60 degrees and the ratio of height (Y) to width (X) can range from0.25 to 4. Similar to the example in FIGS. 4-10, the spacing (S) betweenthe helical vanes 80 can also vary. Other combinations are possible andcontemplated.

The examples shown in FIGS. 10-13 utilize twisted helical vanes, i.e.single twisted vanes having 90 degree twist angles (A). In alternateexamples, the helical vanes 80 could be multi-vane, having for exampletwo vanes per location and a central hub. In the examples shown, thehelical vanes 80 are all rotationally right-handed with respect to theaxial flow path 22. In alternate examples, the helical, vanes 80 couldall be left-handed with respect to the axial flow path 22, or theplurality of helical vanes 80 could include both right-handed andleft-handed helical vanes to induce additional vortexinteraction/dissipation. As illustrated, the helical vanes 80 have aconstant helical pitch (P). In other examples, the helical vanes 80could have compound pitch and/or complexly curved surfaces to maximizethe amount of vorticity or swirl for a given pressure drop caused by thepresence of the helical vanes 80. The helical vanes 80 could also bearranged in an axially staggered pattern, wherein certain helical vanes80 are located further upstream and/or downstream of other helical vanes80 in the plurality.

The present disclosure thus provides a carrier frame for a primary orsecondary (safety) filter element that is configured with integratedvortex-generating features, such as tilted trapezoidal tabs or helicalvanes that promote rapid mixing and quicker establishment of uniformvelocity profile downwind where a MAF sensor is located, therebyminimizing MAF sensor variation due to imperfect air filterconstruction. The present inventors have recognized that secondary (i.e.safety) filters used in direct flow filter assembly configurationscannot be made perfectly, i.e. the secondary filters have some degree ofnon-uniform pleat spacing, varying pleat shape, embossment variation, oreven base media permeability variation. These imperfections causevariation in the effective permeability of the filter elements, whichthen causes corresponding variation in the localized outlet velocityfrom the filter assembly, which persist downwind to the location of theMAF sensor. This causes the MAF sensor, which senses a fairly smalllocal velocity within the duct, to report slightly differing massairflow with different filters and/or rotational position (i.e. if thefilter is rotated 180 degrees and reassembled). Examples provided in thepresent disclosure enable use of conventional pleated filter elementstructures, while minimizing the MAF sensor variability caused byunavoidable variations in the manufacture of the filter elements.

The concepts of the present disclosure are applicable to differentfilter assemblies from that shown in the drawing figures. For example,when direct flow filters are used in on-highway applications, thesecondary filter element typically is not used. Although the velocityjet exiting the gap of direct flow primary filter elements helps toreduce the flow variations caused by filter imperfections, theimprovements disclosed in the present application can equally be appliedto these types of arrangements. Also, in arrangements where airflowenters the gap of the direct flow primary filter, a diverging flow pathis created downstream which can result in a non-uniform velocity profileat the MAF sensor. Many primary filters in automotive applicationsinclude deep pleated or rolled constructions which present the samechallenges as described herein for the direct flow secondary filterelement. The concepts of the present disclosure can equally be appliedto these types of arrangements.

The drawings figures thus depict a carrier frame supporting an airfilter element having a dirty air inlet and a clean air outlet andfiltering air flowing therethrough from upstream to downstream. Thecarrier frame has an exit side at the clear air outlet. The exit sidehas a vortex-generating flow guide promoting rapid mixing of clean airdownstream of the air filter element and normalization of a uniformvelocity profile downstream thereof for flow to a mass air flow (MAF)sensor, to minimize MAF variation due to imperfect air filter elementconstruction. The noted air filter element can be at least one of aprimary filter element and a secondary or safety filter element. The airfilter element can include a pleated filter media. The air flows throughthe clean air outlet along a generally axial flow path until the airflows along the vortex-generating flow guide, which redirects the airflow into at least one vortex flow path.

In certain examples, the vortex-generating flow guide can include totilted trapezoidal tab that extends at a tilt angle with respect to theaxial flow path. The tilted trapezoidal tab can be planar and haveparallel opposing elongated upstream and downstream edges that extendperpendicular to the axial flow path. The tilted trapezoidal tab furthercan have opposing elongated side edges that extend from the upstreamedge to the downstream edge, wherein the upstream edge is longer thanthe downstream edge. The tilted trapezoidal tab can be tilted at anangle of 10-45° with respect to the axial flow path.

The tilted trapezoidal tab can be one of a pair of tilted trapezoidaltabs that have the same geometry and that are tilted at opposite butequal angles with respect to the axial flow path. The pair of tiltedtrapezoidal tabs have adjacent upstream edges and spaced apartdownstream edges. The pair of tilted trapezoidal tabs form a V-shapewhen viewed in cross-section. The pair of tilted trapezoidal tabs can beone of a plurality of pair of tilted trapezoidal tabs that have the samegeometry. The plurality of pairs of tilted trapezoidal tabs can form aradially staggered array of pairs of tilted trapezoidal tabs thatcomprise first and second rows of pairs of trapezoidal tabs. The firstrow has less pairs of trapezoidal tabs than the second row. The pairs oftrapezoidal tabs in the first row are radially offset with respect tothe pairs of trapezoidal tabs in the second row. The first row of pairsof tilted trapezoidal tabs have elongated upstream edges. The second rowof pairs of tilted trapezoidal tabs have elongated upstream edges. Theupstream edges of the pairs of tilted trapezoidal tabs in the first roware parallel with respect to the upstream edges of the pairs of tiltedtrapezoidal tabs in the second row. A plurality of spaced apart crossribs support the array of pairs of tilted trapezoidal tabs.

In certain examples, the vortex-generating flow guide can comprise ahelical vane. The helical vane can comprise an elongated upstream edgeand an elongated downstream edge. The upstream edge is transverselyorientated at a twist angle with respect to the downstream edge. Thehelical vane comprises opposing helical side edges extending between theupstream and downstream edges and a helical surface between the upstreamand downstream edges and between the opposing helical side edges. Thehelical surface directs air flow into the vortex flow path.

The helical vane can be one of an array of helical vanes including firstand second rows of helical vanes. The first row of helical vanes can beoffset from the second row of helical vanes. The helical vanes in thefirst row can have upstream edges that are radially transverselyorientated from upstream edges of the helical vanes in the second row. Aplurality of spaced apart cross ribs can support the staggered array ofhelical vanes.

The carrier frame can be supported in a housing. The air filter elementcan be supported in the housing by the carrier frame, which provides afirst seal between the carrier frame and the air filter element and asecond seal between the carrier frame and the housing, therebypreventing bypass of unfiltered dirty air to the MAF sensor in the eventof a rupture or damage to the air filter element.

What is claimed is:
 1. A carrier frame supporting an air filter elementhaving a dirty air inlet and a clean air outlet, the air filter elementfiltering air flowing therethrough from upstream to downstream, thecarrier frame comprising: an exit side positioned downstream andadjacent the clean air outlet; and a vortex-generating flow guidemounted on the exit side, the vortex-generating flow guide comprising: aplurality of spaced-apart cross-ribs; and a radially staggered array ofpairs of tilted trapezoidal tabs mounted on the plurality ofspaced-apart cross-ribs, each of the pairs of tilted trapezoidal tabscomprising: a first upstream edge having a first end and a second endand a second upstream edge having a third end and a fourth end mountedon a cross-rib, the first upstream edge extending along a first lengthof the cross-rib and the second upstream edge extending along the firstlength of the cross-rib such that the first end of the first upstreamedge is aligned with the third end of the second upstream edge and thesecond end of the first upstream edge is aligned with the fourth end ofthe second upstream edge, and a first downstream edge and a seconddownstream edge positioned downstream from the cross-rib, the firstdownstream edge spaced apart from the second downstream edge, whereinthe vortex-generating flow guide promotes rapid mixing of clean airdownstream of the air filter element and normalizes a uniform velocityprofile downstream thereof such that mass airflow variation is minimizedfor flow to a mass airflow sensor positioned downstream of thevortex-generating flow guide.
 2. The carrier frame according to claim 1,wherein the first upstream edge and the second upstream edge are longerthan the first downstream edge and the second downstream edge; andwherein the pairs of tilted trapezoidal tabs have opposing elongatedside edges that extend from the first upstream edge and the secondupstream edge to the first downstream edge and the second downstreamedge.
 3. The carrier frame according to claim 1, wherein the pairs oftilted trapezoidal tabs form a V-shape when viewed in cross section. 4.The carrier frame according to claim 1, wherein the carrier frame issupported in a housing, the air filter element is supported in thehousing by the carrier frame, the carrier frame provides a first sealbetween the carrier frame and the air filter element, and the carrierframe provides a second seal between the carrier frame and the housing,thereby preventing bypass of unfiltered dirty air to the mass airflowsensor in the event of a rupture of or damage to the air filter element.5. The carrier frame according to claim 1, wherein the air filterelement comprises at least one of a primary filter element and asecondary or safety filter element.
 6. The carrier frame according toclaim 5, wherein the air filter element comprises a pleated filtermedia.
 7. The carrier frame according to claim 1, wherein the pairs oftilted trapezoidal tabs are tilted trapezoidal tabs having the samegeometry and are tilted at opposite but equal angles with respect to theaxial flow path.
 8. The carrier frame according to claim 7, wherein theradially staggered array of pairs of tilted trapezoidal tabs have thesame geometry.
 9. The carrier frame according to claim 8, wherein theradially staggered array of pairs of tilted trapezoidal tabs comprisesfirst and second rows of pairs of trapezoidal tabs, the first row havingless pairs of trapezoidal tabs than the second row; and wherein thepairs of trapezoidal tabs in the first row are radially offset withrespect to the pairs of trapezoidal tabs in the second row.
 10. Thecarrier frame according to claim 9, wherein the first row of pairs oftilted trapezoidal tabs have elongated upstream edges and the second rowof pairs of tilted trapezoidal tabs have elongated upstream edges; andwherein the upstream edges of the pairs of tilted trapezoidal tabs inthe first row are parallel to the upstream edges of the pairs of tiltedtrapezoidal tabs in the second row.
 11. The carrier frame according toclaim 1 wherein the air flows through the clean air outlet along agenerally axial flow path until the air flows along thevortex-generating flow guide, which redirects the airflow into at leastone vortex flow path.
 12. The carrier frame according to claim 11,wherein the pairs of tilted trapezoidal tabs extend at a tilt angle withrespect to the axial flow path.
 13. The carrier frame according to claim12, wherein the pairs of tilted trapezoidal tabs are planar and thefirst and second upstream edges and first and second downstream edgesextend perpendicular to the axial flow path.
 14. The carrier frameaccording to claim 13, wherein the pairs of tilted trapezoidal tabs aretilted at an angle of 10 to 45 degrees with respect to the axial flowpath.
 15. The carrier frame according to claim 11, wherein thevortex-generating flow guide comprises a helical vane.
 16. The carrierframe according to claim 15, wherein the helical vane comprises anelongated upstream edge and an elongated downstream edge, wherein theupstream edge is transversely oriented at a twist angle with respect tothe downstream edge.
 17. The carrier frame according to claim 16,wherein the helical vane comprises opposing helical side edges extendingbetween the upstream and downstream edges.
 18. The carrier frameaccording to claim 17, wherein the helical vane comprises a helicalsurface between the upstream and downstream edges and between theopposing helical side edges, the helical surface directing the airflowinto the vortex flow path.
 19. The carrier frame according to claim 18,wherein the helical vane is one of an array of helical vanes thatcomprises a first and a second row of helical vanes.
 20. The carrierframe according to claim 19, wherein the first row of helical vanes isradially offset from the second row of helical vanes.
 21. The carrierframe according to claim 20, wherein the helical vanes in the first rowhave upstream edges that are radially transversely oriented fromupstream edges of the helical vanes in the second row.
 22. The carrierframe according to claim 19, comprising a plurality of spaced-apartcross-ribs that support the staggered array of the helical vanes.